I think it’s very important for a musician to be able to judge the quality of instruments he plays. This certainly requires direct experience and a certain sensitivity, which are not acquired just by reading a short text like this. However I believe that knowing straight away what the most important issues are and where to focus one’s attention, will be a great help for many.
Unfortunately it would be a lie, if I’d say that most of the clavichords I got to play were great instruments. These have often been treated coldly by colleagues, because they bring more problems than income: information is for many instruments rather scarce and one has to rely on his experience; but the demand is limited and one gets hardly enough requests to be able to devote himself toroughly to the peculiar problems of this instruments. If you ask around, builders will tell you that building a good clavichord is much more difficult than building a good harpsichord. And yet almost no one would be willing to pay for a good clavichord the equivalent of a very average harpsichord. The consequence is that many, avoid devoting too much effort to it.
On the other hand, it is unfair to place all the blame on the builders, when the customers themselves do not seem willing to appreciate and reward quality: common sense tells that the clavichord is in fact just a rectangular wooden box with keys, strings and not much else. It doesn’t seem to require that long to build that and so prices are expected to be very low.
The truth is that if you’re an amateur who’s actually just looking for “a box with keys and strings” and doesn’t care much about the musical side, then, yes, it doesn’t actually take long to get it done. If you’re happy with it, who am I to judge?
But if you want a good clavichord, that is, an instrument that inspires at a high level and on which it is really worth to make music, then things get very complicated and it requires all the experience and knowledge of a professional. In this case even the amount of work is comparable to a harpsichord.
But how to recognize a good clavichord? The features you need to focus on are essentially two: touch and sound. Since one usually doesn’t have much time to try an instrument, I suggest you don’t waste too much evaluating decorations and joinery: first because to correctly evaluate several details of craftsmanship one also needs a bit of direct experience; second because, for better or worse, aesthetics have little impact on the musical quality of instruments. The first and most important advice you’ll ever get in judging an instrument is therefore: close your eyes and let your fingers and ears tell you what they feel.
As for the touch, if you have never played a clavichord, I highly recommend you try one which is certainly good first, were they not so rare. Anyway, what you will feel in a good instrument, is the right resistance of the strings to the pressure of your finger. This is in itself both good and necessary as far as it ensures good contact between strings and tangent. Unfortunately to whomever is not used to the instrument, this resistance often seems excessive: the next problem is therefore how to establish if it’s right or not. The best technique to produce sound on the clavichord is to let the weight of your arm rest on the finger. Playing in this way, the effort must not be excessive: the sound must be sweet, crisp, good-breathed and it must allow a good dynamic range without the intonation to suffer. The bottom of the key must have a minimum of elasticity, which then allows you to play vibrato with some ease by modulating the weight.
If the resistance to touch is too little, the instrument will sound thin, insipid and flaccid; varying the pressure on a note, as in the vibrato, it’s possible to raise the pitch even by half a tone, which limits the dynamic possibilities and makes it hard to play in tune; In worst cases, by playing forte, it is even possible to lift the treble strings from the bridge with the pressure of the fingers. All these are bad signals, because obviously those who built the instrument understood little about some basic issues.
If after repeated attempts with this weight technique, the sound still tends to block all the time and the tangent bounces on the strings because of the tension; if the sound is constrained, acid and ill-breathed, then maybe the stringing is too heavy. In this case the bottom of the key has little elasticity and feels like resting on a solid object: the fingers almost take a slap while playing and the vibrato is difficult to achieve. An instrument with too much tension is not ideal because the sound tends to be cramped, the strings break too often and, while playing, too much of concentration is spent in the effort not to block the keys instead than in making music.
Objectively, however, it is also a matter of habit and taste: what for somebody is too heavy, for others is perfectly acceptable. In general, be aware that the probability of you being in front of an instrument with too a high sting tension, is low; also in this case sometimes it is enough to lower the pitch by half a tone to have significant improvements.
To evaluate the sound, however, my first advice is to take the trouble to listen to good recordings of ancient instruments. I must emphasize the adjective “good”, because I happened to listen to recordings of instruments in less than optimal conditions. The most problematic instruments are, as always, the oldest ones: since they are so little known, even restorers, curators and musicians have little reference. For this reason I had to hear recordings of renaissance-clavichords in which between key noise, incorrect stringing and poor playing technique, the instruments sounded like a box full of crickets. Look for a good recording and you won’t regret it: you will notice how sweet, warm, focused, intense, resonant antique instruments sound and how they seems to have a very deep breath.
In this regard Jacob Adlung, describing a good clavichord, wrote: “A clavichord must sound loud, yet not percussive, but rather sweet and harp-like. It must also have a sweet and long voice.” It sounds pretty simple as a description, but he actually spots some of the more crucial aspects.
First of all, a clavichord must sound loud. The particularly feeble instruments, which are so often encountered, are clearly not to be considered particularly good. Loud is certainly relative, because it is physically impossible for a clavichord to match the organ of Freiberg’s Cathedral in volume. The absolute decibels, however, do not matter that much, because an intense and well structured tone arrives directly to our mind: if the instrument is good, it will be perceived without any effort in a fairly large room; hence the feeling of loudness. Just to give it a more practical measure, a good clavichord should ideally be able to accompany a violin with sordino or a flute.
The second problem is more subtle and here Adlung is also right: because of the way the sound is produced, it is easy that acting to maximize the volume output will also increase the noise. In this case the attack-noise, then tends to give the instrument a percussive character that can be unpleasant. The tenor is the area most sensitive to this effect.
The sound of a good clavichord must remember that of a harp or a lute and in fact good historical instruments show this character. The sound in the soprano, although solid, is sweet, “hollow” and well resonant: it shows a “woody” character and the metal of the strings passes in the background. At this point each note becomes the pearl of that series mentioned by C. P. E. Bach in his treatise. On the other hand, if you feel the metal more than you perceive the wood and if the sound is constrained and flabby or acerbic, thin, breathless and with a rich inharmonic component, the instrument is not very good.
Last aspect mentioned is the decay of sound; this is also in contrast with other elements: the more efficient the energy distribution (high sound volume), the more energy will be used up quickly through the board with a rapid decay. Since the energy produced by the impact of the tangent on the string is very little, the balance of elements such as sound volume, percussion noise and decay is much more critical than in any other keyboard instrument.
For this reason, in the prosecution Adlung also points out how difficult it is to build a good clavichord: since every part of this seemingly simple instrument, performs more than one function, failing even on a single element ends up spoiling the sound significantly. If a harpsichord or a piano which are less than optimal, sound just less well; a clavichord barely whispers and you risk finding in your hands the “box with keys and strings”, I was talking about before.
You may have noticed that I omitted one aspect that is commonly considered among the most important: i.e. the balance between the various areas of the instrument. I did this on purpose, because it is an aspect that deserves some discussion: if having a “hole” in a region of the instrument is definitely a flaw, on the other hand I am not convinced that all good instruments are meant to have a sound really homogeneous in all registers. Some great clavichords are more colorful and more responsive in some areas, others in other areas, and this could undoubtedly be an intentional feature more than a fault. It should be noticed that, organ stops, human voice and most instruments, all do not have a homogeneous response. More over at the clavichord this disturbs very little, because through the dynamics on a good instrument it is always possible to bring out what one wants.
These are more technical than artistic aspects. But an instrument for a musician is almost like a part of the body and therefore it must in some way also speak to the spirit or it will always remain a clumsy prosthesis. When you want to know if a musical instrument of any kind has a good character, the best way is to start by improvising: by not imposing a too much defined musical content, you can listen to where the instrument wants to bring you. I am unfortunately a bad improviser, because in my musical training this discipline was always neglected, which I regret; but in this case it is a good indicator: if my improvisations sound interesting, then the instrument is necessarily great; if they sound trivial, then it’s nothing special. The difference is in the quality of the instrument, a bit like when different actors read the same text.
By placing yourself in an open way towards the instrument you can see if it inspires musical ideas or not; and whether it “adulates” or “humiliates” our efforts. The best instruments are so fascinating, that make seem interesting even the most modest musical ideas, while a bad instrument does nothing but expose and ridicule your best efforts. In this way a good instrument gives confidence, because no passage sounds really wrong and you can always find your way out even in weird harmonic or melodic situations. On the other hand they catch your ear, so you would play and improvise for hours without getting tired. In essence, the most valuable instruments encourage us to improvise because they stimulate imagination, attention and pull fear away.
The situation turns around on the instruments, which seem willing to expose every flaw in our execution and suggest no musical ideas. In the end, one feels like being mobbed. The more one plays, the less our brain becomes interested in predictable and lifeless sound, until it goes in “standby-mode”, making the musician’s task even more difficult.
With this text I hope ho have given some useful indication on how to judge the musical value of a clavichord. Some ideas might remain obscure, others will sound strange and perhaps you won’t like some other at all. But be kind, because it is not an easy subject to deal with; and on the other hand with experience you probably will understand what I mean here.